XCR-L Aftermarket or Binary triggers
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I talked about this topic in this thread: TRIGGER DISCUSSION
I think the triggers have to be specifically designed to allow for binary function on the XCR, since Franklin Armory has triggers for several different guns right now. I would really have to examine the design of the binary trigger to see if it's possible for me to make one of my own. I think a better question to ask is how the XCR's trigger system differs from the AR-15's and then determine what needs to be modifed to get it to work.
I think the triggers have to be specifically designed to allow for binary function on the XCR, since Franklin Armory has triggers for several different guns right now. I would really have to examine the design of the binary trigger to see if it's possible for me to make one of my own. I think a better question to ask is how the XCR's trigger system differs from the AR-15's and then determine what needs to be modifed to get it to work.
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That's not too big of a deal now that we know there is a stock adapter for the XCR to fit the ACR's stock, and most other accessories can be screwed onto its keymod slots like anything else out there. I must be insensitive to it or too new to this but I'm fine with the trigger as-is even in a competitive match setting. A binary trigger would be fun and if you have machining skills, I don't see why it won't be possible to make one. I just don't understand how the binary trigger is able to force the hammer to strike again on the back pull of the trigger (it would help if I had one to examine). The XCR's hammer looks just like that of an AR-15's but I'm not sure of any of the differences outside of it.
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Rumor the forum, Alex wanted a shorter lower. It would have to have been about .25" taller to work with an AR trigger. I think someone squeezed in a cmc(?) trigger into a xcr way back but it took some machining. I haven't looked in a long time but I thought the layout/spacing on the pins and safety were pretty close to the AR pattern. Larger barrel on the xcr safety.
FWIW, I asked lingleindustries.com about a custom lower with AR fcg, built in 1913 stock adapter in AR and AK mag versions. He said I wasn't the first to ask. They're just getting started and they aren't a FFL yet. Send them some messages TY let them know there's interest.
FWIW, I asked lingleindustries.com about a custom lower with AR fcg, built in 1913 stock adapter in AR and AK mag versions. He said I wasn't the first to ask. They're just getting started and they aren't a FFL yet. Send them some messages TY let them know there's interest.
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Just sent an email. Surprised how inexpensive their lowers are frankly.
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I told him the same. He didn't give me a time line though. A year is a little disheartening.
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Yeah...with the current climate, probably won't matter....but I wish him the best.
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Just looked at their offerings. Make me wish RA had serialized the upper instead. AK/STANAG lower swaps would be so awesome.
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Yeah, mixed bag. OTOH, serialized upper would be cool....for lower swaps....but I've swapped a fair amount of uppers (from railed to KM to competition, to mini and standard). It would be better if we just didn't have NICS at all.
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Interesting idea, actually. You think the dimensions on the upper would change much if they serialized it? Are we on the 3rd revision of the XCR right now? Maybe the next revision they could serialize both the upper and lower, so that if you don't get a complete rifle from RA, you could build around it with their parts. A shorter lower ought to be an advantage for some AR-15 builders, and having unified uppers are a premium AR product - it's sure to be competitive when LMT has got it hands busy.
Fascinating. With luck, it's possible that all you would need to do is CNC machine a hammer that's compatible with the XCR and drop it into the binary trigger. I really need to examine a binary trigger though, because I don't know if there is something about the hammer in it that helps with the binary fire function. I think I'll get one just to examine when my budget is able to breathe.
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Ok, so thanks to this Youtube video we have a more in-depth look at the Frankin Armory Binary Trigger. I fully suspect that the hammer of the XCR trigger is shorter than that of an AR, and the gentleman in the video states that the secret in the binary trigger sauce is mainly in the trigger itself, the hammer is pretty much like an AR hammer. Two issues. First is a major issue, I'm concerned that the XCR trigger is also low profile and the binary trigger would sit higher than it. I don't think RA would reinvent the wheel and I suspect the seat where the trigger sits and the safety location are similar to an AR trigger group. A second more minor issue is the fact that the XCR, of course, does not have a buffer tube, while the binary trigger package includes a buffer tube spring. I believe this spring is specific to help the binary trigger reach its timing as the BCG moves over it to achieve binary fire. The stock recoil spring in the XCR may or may not cause issues with binary trigger action; it's the disconnector hook on the trigger that's the primary actor in the binary function and that can be adjusted according to the specific system.
I'm going to get some measurements on the trigger in the XCR vs a typical AR and see if there are any differences in height. If I get a good feeling about this, I'll try getting a binary trigger from my local gun store and see if I can get it to work. I suspect that I can use the stock XCR hammer and just use the trigger, disconnector hook, and safety switch in the Binary Trigger package, leaving out the buffer tube springs. I always wanted to use the binary trigger for something but, long term, I want my XCR to stay semi-auto as Robinson made it. I just hope this kind of discovery would help alleviate the chronic, terminal boredom I see on this fan base.
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Aside from quad rail, to keymod and now M-lok, I don't think the upper receiver has changed much. If the upper was the serialized part, like the SCAR, then owners could purchase and swap lowers without having to deal with FFL transfers—making the XCR even more modular. And why would we want that? AR-pattern mags for 7.62x39 suck. Some of use would love to have lowers that take AK mags. On a tangent... Franklin Armory is said to be evaluating reboot of the Bushmaster ACR/Masada. This is the route I'd like to see them take.
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Right, so before Sean or someone jumps down my throat about this, I took a closer look at the trigger group in the XCR last night and noticed that it is COMPLETELY different from from the AR-15 trigger or just about any other trigger group I can find. Among other things, the disconnector stops the hammer using a kind of c-shaped hook that grabs into a peg on the side of the hammer. There is nothing in the Frankin Armory catalog or anything in the aftermarket like it. I can only imagine the kind of time and R&D that was needed just it make this thing.
While that project was a bust, the theory in designing a binary trigger from the ground up is still sound. Instead of modifying my stock trigger or ordering and modifying a spare trigger from RA, I think it would be best to design a binary trigger in Fusion 360 and CNC one from scratch. I do intend to preserve the rifle up to the hammer in the design while making a trigger, disconnector and mode select switch that are conducive to binary fire. Though with my luck, I might end up accidentally making an uncontrollable auto sear.
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It's hard to tell when I don't have an AR lower to compare and the schematic on the Robinson site is outdated and does not show the trigger that is being used for the 2018 models. Do you know an updated one? Perhaps with dimensions etc?
That's a good idea though; if the pins and safety line up with an AR trigger, we could still replace everything and machine a new hammer/trim down the one included with the binary trigger. Something tells me that is unlikely, but if it works it would be a lot easier to rig up but cost more out of pocket.
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Not sure why you chose to call me out specifically, but hey, whatever. You basically invited the following response by singling me out, so here it is:
You don't own an AR lower that you can cross measure to see the pin difference?.....which makes me wonder if you've actually shot one.
Do you actually own a binary trigger? I do. They suck in terms of the quality of the break and reset in semi-auto mode. The one I have and all the ones I've fired (Fostech, Franklin Armory) have the same gritty feel and have a lot of travel in uptake and reset. They're sorta fun in binary mode, though I can run a really good, short reset trigger almost as fast so to me, there's little point and for the price tag of $300+ (depending on model)....I'd rather spend $240 or a good deal less on a good, recognized name brand trigger with short overall travel (I have ones that are under 1/8" of TOTAL travel); clean, smooth take up and a crisp break along with a very short reset.
I would potentially buy one more to put in a S&W M&P15-22 7" "pistol" with a can on it b/c it'd be a fun toy. Otherwise, they aren't that great, IMO. YMMV.
EDIT though now that I think about it...apparently there are some AR triggers that fit in the M&P15-22. I'd go that route over a binary...for less than half the cost***
You're talking about cadding one up in F360 and then doing a CNC run. Do you actually have access to the CNC equipment to do so? If so....you've got a real shot at fixing the problems with those other designs. If not, it's unlikely a CNC shop is going to want to prototype this for you and sintered metal printers are out of the realm of most folks...but that could be another viable prototype method.
Good luck with it and let us know how it goes. 😃
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